Toxicidade aguda em eleuteroembriões do jundiá Rhamdia quelen submetidos ao extrato hexânico de Ricinus communis

Abstract

Botanical extracts present insecticidal activity on target organisms, but on non-target organisms need to be investigated. The aim was to evaluate survival and toxicological parameters, such as morphological deformities, mobility, cardiac output and DNA fragmentation, in eleuteroembryos of Rhamdia quelen submitted to hexane extract of Ricinus communis. To determine the concentrations of this work, the lethal concentration (CL50) of the hexanic extract obtained for Chrysodeixis includens, soybean caterpillar (target species) was used as reference. The following dosages were evaluated: (D1) 50% of CL50, (D2) 25%; (D3) 12.5%; (D4) 6.25%; (D5) 3.12%; (D6) 1.56%; (CTR) Negative control; (CTRV) Vehicle control. Viable eggs were placed in 96-well ELISA microplates, in the respective treatments. Each treatment occupied three columns of the microplate, requiring two microplates to count a replica. Eighteen replicates were used and two exposure times were sampled for most analyzes. The hatching rate was evaluated at 28hpf and survival at 48hpf, 72hpf and 96hpf. The highest concentrations of the extract (D1 = 1%, D2 = 0.5%, D3 = 0.25% and D4 = 0.125%) unviabled the hatching or caused high lethality. The eleuteroembryos survive was similar between D5, D6, and controls. Morphological deformities were observed mainly in D5, with craniofacial damage, lordosis, body atrophy and fins lesions. Mobility and cardiac output were similar between the CTR, D5 and D6 groups, except to cardiac output in 48hpf (lower). The CTRV group showed lower values in both parameters. No significant difference was observed in the rate of DNA damage between the surviving groups. The concentrations D5 and D6 present higher potential for prospecting for a new phytosanitary agronomic product, because they presented low toxicity to the eleuteroembryos.